The present invention relates to an apparatus and method for cleaning container closures by removal of contaminants shortly before the closures are applied to bottles or other containers by a capping machine. More particularly, this invention relates to an apparatus and method for directing sprays of liquid and gas against inner surface portions of the closures, while forcing the closures along a chute leading to the capping machine.
Thorough cleansing of closure interiors poses a difficult problem inasmuch as the closures may be traveling from hopper to capping machine at rates of 250 to 1000 closures per minute, and typically travel at a rate of about 400 to 800 closures per minute. A multiplicity of waxes, oils and pigments is applied to the closure interiors for various purposes, further increasing the difficulty of removing contaminants. Waxes and oils on interior surface portions of the closures may bond particulate contaminants to the closure surface. Although the types of particulate contaminants usually found on closure surfaces do not normally pose a health hazard, these particulates may be visible to the consumer, thereby deleteriously affecting consumer acceptance of the packaged product.
Several devices similar to the closure cleaning apparatus of the present invention have been developed in the prior art. However, each of these prior art devices suffers from one or more serious limitations making it less than completely suitable for its intended purpose.
For example, Green U.S. Pat. No. 2,367,393 discloses a closure cleaning device including a compressed air jet directed toward the interiors of closures passing down a chute from a hopper to a capping machine head. However, the Green device lacks any provision for cleaning the closures by means of water or other liquid, and directs its air stream at an acute angle to the flat cap portions of the closures. This angularly oriented air stream is intended to assist movement of the closures along the chute and through a suction zone where contaminants are removed. The Green device lacks any means for controlling velocity of closures moving down the chute, thereby limiting thoroughness of cleaning necessary to assure consistent quality control in the finished product.
A more sophisticated closure cleaning device is shown in Wilde et al U.S. Pat. No. 4,167,797, issued Sept. 18, 1979. This device is mounted at the terminal of a crown feed track just prior to the point where closures are transferred to the capping machine of a bottling line. The device includes a liquid spray jet and several air spray jets, each of which directs a fluid spray at an acute angle to closure caps passing down the feed track. Unlike the apparatus of the present invention, the Wilde et al device lacks any provision for directing a fluid spray generally perpendicular to the cap interiors and does not control velocity of the closures by means of a belt engaging the closures.
Elliott U.S. Pat. No. 3,965,523 discloses a bearing washing machine for cleaning bearings having a large diameter, generally cylindrical outer race and a smaller diameter, generally cylindrical inner race connected to the outer race and concentric therewith. The washer conveys the bearings through a housing on two laterally spaced, parallel chains. Diametrically opposite portions of each outer race are supported on the chains with the inner race being freely rotatable during passage through the housing. The chains are driven by a motor to pass underneath a sequence of washing solution nozzles 42, high pressure air nozzles 45 and drying air hoses 46. However, in order to urge inner races of the bearings into rotation, the washing nozzles 42, high pressure air nozzles 45 and low pressure nozzle 47 are directed toward the inner races in a downwardly oblique direction, as shown in FIGS. 7 and 8. In contrast, in the present invention, it has been found highly desirable to direct sprays of cleaning water and air generally normal to the inner surfaces of closure caps rather than at an oblique angle. The cleaning apparatus of the present application also differs from Elliott's bearing washer in that there is here provided a dead plate adjacent inner surface portions of the principal section of the belts, thereby limiting inward displacement of the principal section upon exposure to high pressure sprays of water and air.
An apparatus for removing loose particles from can interiors is shown in Taylor U.S. Pat. No. 1,689,757. Cans passing sideways along a conveyor belt are flushed to remove loose particles and moisture by three air nozzles mounted parallel to the plane of the conveyor belt. The nozzles are inserted into the can interiors, thereby making the Taylor apparatus unsuitable for use in the high speed operations of modern packaging plants. Taylor further fails to suggest that the air nozzles should be directed normal to the plane of the conveyor belt rather than parallel thereto.
Walberer U.S. Pat. No. 2,917,768 discloses a machine for suction cleaning of wide-mouthed jars prior to filling in a canning factory. The jars are fed to a suction nozzle by passing along a conveyor belt. The Walberer patent lacks any suggestion that its means for suction cleaning of wide-mouthed jars should be combined with other prior art devices for removing contaminants from closure cap interiors.